chronic kidney disease

New research determined a link between potassium levels, with the risk of developing chronic kidney disease in a mostly white population.

 

Potassium is a mineral that aids in proper bodily functioning. Levels of potassium are tightly regulated by the kidneys to help control blood pressure. In chronic kidney disease, a condition that results from kidney malfunction, patients may suffer from unregulated potassium levels in the blood. Hypokalemia is a condition when potassium levels are low (<3.5mmol/L) and hyperkalemia (>5.0 mmol/L) results from increased levels of potassium. Chronic kidney disease (CKD) patients with either hypo or hyperkalemia have a higher risk of mortality, heart attack, and hospitalization. Previous kidney studies have also found that hypokalemia may lead to kidney damage. However, the evidence demonstrating the association of hypokalemia with risk of developing CKD is not yet established.

In a recent study published in Plos One, researchers conducted a prospective study to examine the association between potassium blood level and the risk for developing CKD in predominantly white population. The study enrolled 6,000 participants with a urinary albumin concentration of 10 mg/L, a metric for hypertension and risk for CKD. Furthermore, the study also enrolled 2,592 participants with <10mg/L urinary albumin concentration. Participants who were diabetic, who already suffered from CKD and who were pregnant were excluded, leaving 5,130 participants. Circulating potassium levels, glomerular filtration rate (GFR), serum creatinine, and cystatin C were measured. Hypokalemia was defined as <3.5 mmol/L, normokalemia at 4-4.4 mmol/L, and hyperkalemia at a concentration equal to or greater than 5.0 mmol/L. CKD was determined by low GFR (<60ml/min per 1.73m2) and/or low urinary albumin excretion (UAE) (> 30mg/24h).

The researchers found mean plasma potassium levels of 4.4 mmol/L across the 5,130 participants. Hypokalemia had a low prevalence at 0.5% while hyperkalemia was slightly more common with a3.8% prevalence. Interestingly, participants with hypokalemia do not consume alcohol or smoke.  They were also likely to be older, less educated and have high blood pressure as well as likely users of beta blockers and diuretics. In contrast, participants with hyperkalemia were likely to be male, to smoke, and to be White. They also have a higher UAE and non-usage of diuretics.

With regards to hypokalemia and risk of CKD, with a median follow-up of 10.3 years, researchers found that 753 participants eventually developed CKD. Participants with hypokalemia were about 5 times likely to develop CKD than those with normal potassium levels, and the risk further increased in participants who used diuretics. Participants with hyperkalemia, however, were not likely to develop CKD. Furthermore, the link between potassium levels with the risk of developing CKD changed when subjects used diuretics. In non-hypokalemic participants who used diuretics, researchers found an increased risk of CKD. Overall, the researchers concluded that hypokalemia was associated with a higher risk of CKD regardless of use of diuretics. The precise mechanism as to how hypokalemia induces kidney damage remains unclear. The current study could not yet be generalized to a broader population due to a lack of diversity in the participants. It remains to be seen whether a similar association between hypokalemia and CKD would be observed for other patients from other racial ethnicities.

 

Written By: Joan Zape, PhD(c)



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